Cell Internal Resistance Meter

[Anders]

Hello.

Have anyone tried this meter yet from http://nqrc.com/

I saw this IRM on http://www.rcgroups.com/forums/showthread.php?t=980290

It look a lot easier to check my cells internal resistance with this than with any other types of equipment, am I right?


I searched for it on the forum but didnt find any info about it.

Anders

 

[VidPro]

you mean this
http://nqrc.com/?vp=PLD-IRM-004

i thought he wasnt done developing it yet, it looks promising.

i bet its a lot CHeaper to check internal resistance with something like this, than the stuff they got out for $300-400 :broke: that is mostly for checking industrial 12v type of cells.


"I have a lot of lipos to try and keep track of which have gone south on me."
well then i guess you dont need a checker for those :-) :devil: just a recycler

it has never taken me very long to determine if a cell i have is usable or not, i am not up 500 feet in the air doing dive bombs into the ground , when i discover it :eek:, like they can be.
what will this do that i cant see with a $25 DMM and the light the battery goes in?

it would probably be perfect for assembling and checking each cell in SERIES, matching them up and all.

 

[Turbo Guy]

A cell IR measurement device is a very good means to grade cells and to track their performance over time. I am very familiar with the Tread on RC Groups and that is a very nice unit however I allready have several chargers which take IR reading during charging.

In very simple terms the lower a cells IR the greater its' ability to deliver amps.. It will stay cooler during discharge and during charging also. Thing is IR varies with cell temperature,state of charge and physical size(capacity) of cell. A 2000 mAh cell will have half the IR of a 1000 mAh cell all other things being equal.

One major problem as I see it when using any device to obtain IR of cells used in flashlight is that most have protection circuites in them which adds to the IR so you can not obtain an accurate IR of the cell.

 

[Anders]

Hello VidPro and Charles.


Thanks for the input.

Yes the PLD-IRM-004 looks promising.

Anders

 

[VidPro]

One major problem as I see it when using any device to obtain IR of cells used in flashlight is that most have protection circuites in them which adds to the IR so you can not obtain an accurate IR of the cell.

but even with protection, or connecting wires and stuff, anything that has the exact same resistance, length of wire, and connectors and stuff, could still be compared to similar items of the same. even if the numbers are miles off from some standard that were supposed to adhere to, or numbers tossed up by some other device, IF using the exact same Unit, a person could get a great comparison anyways right?

if you read the results the RC battery dudes got, basically they had good cells and bad cells, and they knew which they were , before they even tested :-) it would be just like that with me. ohh look at that, that reads exactally as i suspected it would. ohh that puffy cell, what the heck are they keeping a puffy cell for? 4th of july :-)

they should be selling these things to people who have no IDEA how to use them, or how they work, because they NEED them a lot :grin2:, none of that nasty resistance volts checking, just plug and pray.

 

[Turbo Guy]

As I stated earlier the device in question is a very good one however... I am a meat and potatoes kind of guy and the best single battery test device availlable for a reasonable price IMO is the CBAII from West Mountain Radio.

I am more interested in the real capacity of a cell / battery at the load(amp. / mA) that the device it will be used in and its' ability to maintain volts under load at said discharge rate.

 

[snakebite]

this is what i use.
get it without the protection kit for battery testing.
http://www.flippers.com/esrktmtr.html

 

[Meterman]

The PLD-IRM-004 is designed especially for the checkout of cells in packs. So the resistance of the leads inevitably is contained in the resulting Ri.

As I only employ single cells, I am looking for an Ri meter with 4-wire (Kelvin) hook-up, current and voltage measured separately.

Such a version I would be highly interested in.

Wulf

 

[Turbo Guy]

As I only employ single cells, I am looking for an Ri meter with 4-wire (Kelvin) hook-up, current and voltage measured separately.

Such a version I would be highly interested in.

One charger thgat uses Kelvin connections,
FMA Cell Pro 10 charger but only for LiPoly and LiIon. I have had mine for a year and find the IR readings extremely accurate as well as the cell voltage and capacity. Shame it has no discharge function and does not do Ni.

 

[Meterman]

That FMA Cell Pro 10 charger really seems to be a powerful device and apparently uses Kelvin connections. But for me it's not the optimum, as I only use (smaller) single cells and dozends of eneloops.

By the way, I can measure Ri at any desired current using my e-Load (sorry, description only found in german language, but data can be understood for sure), but I must not forget to subtract the resistance of my homemade battery adapter: exactly 9,70.mΩ (so ~10mΩ) and I have to connect the e-Load to a computer. :thumbsdow

Wulf

 

[LuxLuthor]

CE-35 does it

 

[Meterman]

CE-35 does it

Thanks for the hint - an interesting device - but that monster seems to be a little bit too big for single flashlight cells. By the way, a charger not serving LiIon and LiFePO4 seems someway outdated to me. But I really like this passage in the description:

Voltage sensing and current draw leads

The voltage sensing leads (small wires) are not dependant on length. You can make tem any length you want. They need to be connected to something that is soldered directly to the battery. That is why we make them separate from the current wires (large wires). There is a voltage drop at the point where the current jumps from the battery terminal to the current clip. If you solder them to the current clips, or attach them to the current clips, the voltage is being measured after the drop occurs. A typical error would be about .30 volts with a 30 amp discharge rate. That means your 6 cell pack will cut off at 5.70 volts instead of 5.40. The current carrying wires can be lengthened, but if you want to discharge single cells at 35 amps, the wires will need to be kept original length. The calibration of the unit is not dependant on wire length, but its ability to control current at the extremes may be compromised when a lot of wire is added.

What I'd rather buy from that supplyer is the Single cell fixture, Code: CEI-4903 even at the price of $29.95, but - alas - they don't like people outside the USA: :thumbsdow

** Continental US Orders Only **

Somewhat disappointed
Wulf

 

[pldaniels]

Hi everyone,

Paul Daniels here, designer/maker of the IRM-004 that you've been talking about.

I would suggest that you perhaps wait for me to finish the development of the Ni* cell tester which is specifically going to be aimed at only these cells rather than trying to cover the larger spectrum. It'll also be a 4-wire test system so you have the gain of eliminating a lot of other resistances from the test.

Paul.

 

[Meterman]

Hi Paul,

glad to hear that from you, although I'd like to check Ri of all of my different cells (NiMh, LiIon, LiFePO4 and even different primaries for comparison purposes).

Wulf

 

[LuxLuthor]

Hi everyone,

Paul Daniels here, designer/maker of the IRM-004 that you've been talking about.

I would suggest that you perhaps wait for me to finish the development of the Ni* cell tester which is specifically going to be aimed at only these cells rather than trying to cover the larger spectrum. It'll also be a 4-wire test system so you have the gain of eliminating a lot of other resistances from the test.

Paul.

Paul, thanks for taking the time to post here. Looking forward to your new products!

 

[LuxLuthor]

Thanks for the hint - an interesting device - but that monster seems to be a little bit too big for single flashlight cells. By the way, a charger not serving LiIon and LiFePO4 seems someway outdated to me. But I really like this passage in the description:

Voltage sensing and current draw leads

The voltage sensing leads (small wires) are not dependant on length. You can make tem any length you want. They need to be connected to something that is soldered directly to the battery. That is why we make them separate from the current wires (large wires). There is a voltage drop at the point where the current jumps from the battery terminal to the current clip. If you solder them to the current clips, or attach them to the current clips, the voltage is being measured after the drop occurs. A typical error would be about .30 volts with a 30 amp discharge rate. That means your 6 cell pack will cut off at 5.70 volts instead of 5.40. The current carrying wires can be lengthened, but if you want to discharge single cells at 35 amps, the wires will need to be kept original length. The calibration of the unit is not dependant on wire length, but its ability to control current at the extremes may be compromised when a lot of wire is added.

What I'd rather buy from that supplyer is the Single cell fixture, Code: CEI-4903 even at the price of $29.95, but - alas - they don't like people outside the USA: :thumbsdow

Somewhat disappointed
Wulf

Wulf, it is relatively outdated. It does do LiPo and Li-Ion, but not LiFePO4 by automatic algorhythm. Well you can use manual setup choices to do it, but I already have my Hyperion 1210i & eStation that does them if needed. You can set it to run dishcarge graphs that are PC captured for any type of cell, including measured IR, and at any amp rate.

 

[clintb]

CE-35 does it

I have that charger, but pre-LiPo firmware update. It measures, IIRC, relative IR, and actual IR. At the time, I didn't use the IR measurements much since I was getting out of electric R/C's, but will probably use it more once I get the LiPo update and charge my torch batteries.

Great charger, BTW.

 

[LuxLuthor]

Yeah, I have the LiPo updated model, and a sweet PC graphing program (via serial port cable) that works almost as well as the CBA-II.

 

[pldaniels]

A fair amount of development to go yet but here's the starting look at the new 0~2V cell tester. There's a few major noticable differences from the IRM-004 in this beast, namely

1) It's a 4-wire kelvin test setup

2) There's only one test load (0.5R)

3) There's NO protection diode against reverse polarity of the test cell, however this won't be a big problem because even when the cell is reversed the circuitry is protected and I'll probably put a buzzer on the unit too to 'alert' that things are in backwards. The reason for the diode removal is that at the low voltages we're testing it makes it near impossible to get a decent current draw load because the diode drops off a significant percentage of the cell voltage.

4) It's going to be encased in a proper hand-held enclosure and you can plug in different test looms via the mini-XLR plug/socket combo (not yet shown)


Here's a link to a photo of the prototype testing a Sony CycleEnergy NiMH.

http://www.pldaniels.com/electronics/albums/irms-20090401/mpicDSCF0010.JPG

 

[LuxLuthor]

Sweet!